@article{DE_1977_13_4_a0,
     author = {A. D. Avdeev},
     title = {Second order matrix differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {579--591},
     publisher = {mathdoc},
     volume = {13},
     number = {4},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1977_13_4_a0/}
}